5 Answers
5

This is a known problem that you can read about here and see the bug report here.

It appears to be an issue with the Broadcom VideoCore firmware, and the popping is caused by voltage jumps as the audio is enabled and disabled.

There is no current solution to the problem, however you can mitigate it's effect by playing audio continuously, instead of having a gap between songs. A script to do this is provided by ski522 in the same forum thread I posted before.

The issue with the popping has now been fixed, but you need to upgrade your Raspberry Pi's firmware to take advantage of the fix. I had this issue with a brand-new Pi running Linux raspberrypi 3.6.11+ #399 (2013-02-09-wheezy-raspbian). As cited above, this is the history of the audio popping sound issue: